Elevating device for an artificial island or work platform

ABSTRACT

Elevating device for an artificial island or work platform comprising a pontoon 1 or work floor and a number of columns 2 displaceable in vertical direction with respect to the pontoon respectively or work floor by means of the elevating device. At each column 2 the elevating device consists of a number of driving devices having pinions 7-10 meshing with gear racks 3, 4 fixed along the columns 2. In particular concerning its bearing the shafts of the pinions 7-10 are fixed to the pontoon 1 or work floor and consist of a motor, a driving gear and a brake. Each driving device is fixed to respectively form part of a reaction arm 11-14 pivotal around the axis of the output shaft of the driving device. At their one ends 15-19 the reaction arms 11-14 are coupled to the pontoon 1 or work floor through hydraulic cylinders 23-26. At all of the reaction arms 11-14 the hydraulic cylinders 23-26 have a connection 39, 40 from both of the cylinder spaces to a common conduit 41, 42 connecting all of the cylinders 23-26 to each other. Further, means are provided for moving simultaneously all of the valves 31-34 in the closed condition when the motors are put in operation and to open condition when the brakes are put in operation.

The invention relates to an elevating device for an artificial island orwork platform, comprising a pontoon or work floor and a number ofcolumns displaceable in vertical direction with respect to the pontoonor work floor by means of the elevating device at each column saidelevating device consists of a number of driving devices having pinionsmeshing with gear racks fixed along the column, said driving devices inparticular concerning the bearing of the pinion shaft, are fixed to thepontoon or work floor and consist of a motor, a driving gear and abrake.

Such an elevating device is generally known. In said known elevatingdevice one or more pinions mesh with each gear rack and usually, thereare several gear racks per column with meshing pinions. Said pinions aredriven either by hydraulic motors or by electric motors. Duringdisplacement of the pontoon or work floor with respect to the columnsand inversely the forces acting on the pinions are automaticallybalanced. When the motors are stopped the brakes come into operation, inwhich condition howerver, no balancing of the forces acting on thepinions and thus also on the gear racks exists anymore.

The invention has the object to provide an elevating device whereby saidlatter may also be obtained completely.

According to the invention said object is achieved in that each drivingdevice is fixed to respectively form part of a reaction arm pivotablearound the axis of the output shaft of the driving device, in that thereaction arm is coupled at one end to the pontoon or work floor througha hydraulic cylinder, at all of the reaction arms said hydrauliccylinders have a connection from both of the cylinder spaces to a valveadapted to shut off said connection or to connect both of the cylinderspaces to a common cnduit connecting all of the cylinders to each otherand in that means are provided for moving simultaneously all of thevalves into the closed condition when the motors are put in operationand to open condition when the brakes are put in operation. In thebraked condition the hydraulic connection between the cylinders of thereaction arms performs the compensation of differences in forces.

Now, the invention will be elucidated with reference to the drawings.

FIG. 1 shows the principle of the invention.

FIG. 2 is partly a view and partly a horizontal section through adriving device of the elevating device according to the invention.

FIG. 1 shows part of a pontoon 1 and a column 2 provided with gear racks3 and 4 respectively at two opposite edges.

On the pontoon a frame is provided indicated by the parts 5 and 6schematically.

The circles 8, 10 and 7, 9 indicated by dash-dotted lines representpinions meshing with the gear racks 3 and 4 respectively.

Pivotable around the axes of pinions 7 to 10 respectively are reactionarms 11, 12, 13 and 14 having ends 15, 16, 17 and 18 respectively whichare connected pivotably to piston rods 19, 20, 21 and 22 respectively ofhydraulic cyliners 23, 24, 25 and 26.

These cylinders are pivotably fixed to the platform 1 as schematicallyindicated at 27, 28, 29 and 30 respectively.

The reaction arms 11 to 14 each support a motor 61, a brake 62 and agear box 60, not shown in FIG. 1 but in FIG. 2.

Near each cylinder 23, 24, 25 and 26 respectively a valve 31, 32, 33 and34 respectively is situated which is movable from the open conditionshown to a closed condition by means of operating means 35, 36, 37 and38 respectively shown in the upper half of the valves.

In the open condition shown the space above the piston in each cylinder23, 24, 25, 26 respectively is connected to the valve through a conduit39, whereas the space below the piston is connected to the valve througha conduit 40 (see cylinder 23). In the open condition shown of thevalves the conduits 39 and 40 communicate with each other as well aswith a conduit 41, connecting the cylinders on both sides of a column toeach other and connecting all of the cylinders to each other through aconnecting conduct 42 when several driving units are superposed.

The conduit system 41, 42 may be supplied with pressurized liquidthrough a pressure conduit 43 having a one way valve 44 and an operatingsliding valve 45. With said sliding valve 45 a liquid may also bedrained off to a receptacle 46.

The control is such that during the operation of the elevating devicethe connections between the cylinders 23 to 26 are shut off. When thebrakes 62 (see FIG. 2) come into operation then the valves 31 and 34come into the open condition shown in FIG. 1 in which in all of thecylinders 23 26 the same pressure ratios prevail and thereby the sameloads between the pinions and the gear racks. At 47 rubber stops areshown limiting the movement of the reaction arms. They may also belocated at the lower side of the reaction arms. Said stops 47 may absorbthe load during transport over sea, in which the cylinders are notpressurized.

If desired in the hydralic compensation system damping accumulators 48may be provided.

FIG. 2 shows a part of a column 2 with gear rack 4. Meshing with saidgear rack is the pinion 7 the shaft 7a of which is supported in bearings50 and 51 fixed in sections 52 and 53 of frame 6.

A gear box 54 is fixed to frame 6 and has a large gear 55 supported onthe pinion shaft 7a and in meshing relation with a small gear 56 on theshaft a of which a larger gear 57 is positioned cooperating with a smallgear 58 on a shaft 59 of which a driving box 60 is fixed to which box ahydromotor 61 and a brake device 62 are connected.

The box 60 is integral with the reaction arm 11 the end 15 of which isconnected to the piston rod 19. Consequently, the box 60 with motor 61and brake 62 as well as the reaction arm is pivotable around the axis ofthe small gear 58. Due to the high gearing obtained through the gearboxes 60 and 54, for compensation of differences in load at pinion 7 andgear rack 4 only relative low forces are to be expected in the reactionarms and thereby in the hydraulic compensation system.

If the elevating devices are in operation for raising the platform orlowering the columns then the compensation device is out of operation byholding the valves 31 to 34 in the closed condition and the distributionof the driving forces of two or more driving units is effectedhydraulically or electrically through a common supply of the motors.

If the brake forces should be distributed, the valves are brought in theshown open condition by which the reaction forces on the reaction armscan balance each other.

I claim:
 1. In a work platform:a work floor; a frame on said work floor;at least one column extending through an opening in said work floor andthrough said frame and having at least first and second gear racksconected thereto; means for displacing said at least one columnvertically with respect to said work floor and frame; said meansincluding a plurality of first and second elevating devices respectivelyassociated with said first and second gear rack; each elevating devicecomprising: a pinion mounted on said frame and meshing with one of saidgear racks; a reaction arm; a motor, a brake and a driving gear havingan output shaft, all mounted on said reaction arm; said brake and saidmotor being operatively connected to said driving gear; said reactionarm being pivotable about said output shaft and having a free end;gearing interposed between said pinion and said driving gear; hydraulicmeans interposed between said free end of said arm and said work floor,and having a cylinder, a piston in said cylinder and defining therewitha first and second chamber on opposite sides of said piston in saidcylinder; a valve associated with each cylinder and having an openposition and a closed position; and first and second conduitsrespectively connecting said first and second conduits to said valve;and compensation means, common to said plurality of elevating devices,and comprising: conduit means interconnecting said valves; and meansoperatively connected to said valves and to said motors and to saidbrakes, and operable to move said valves to said closed position inwhich said conduit means is shut off from said first and secondconduits, when said motors are in operation, and to said open positionin which said conduit means is connected to said first and secondconduits, when said brakes are in operation.